How to lager a beer
How long has your beer been in the fermenter?
Have you measured the density and does the hydrometer tell us it is stable?
Have you already carried out a racking in a second fermenter to eliminate most of the residues that are deposited in the primary fermentation?
Did you let it rest a few more days?
It would seem that there are no more residues, but the reality is that this beer could be even clearer.
How? With the lagering method.
For those who have never heard of it, this is an exclusive technique for lager beers (as you can already understand from the name) which plans to keep the beer at temperatures close to zero for a long period: at such low temperatures all the residues (yeast, hops, proteins, tannins, sulphides) settle on the bottom, leaving the final product incredibly clear and clean.
HOW TO LAGER WITH ORIGINAL TECHNIQUE?
The term lagering has its origin in the German custom of storing beer inside warehouses (in German lagern) where temperatures, especially in winter, were freezing: in this way the beer was kept intact for some time.
As has been the case with many brewing styles and techniques, lagering was therefore not designed specifically for the purpose of homebrewers today, but was simply a practice in use in Germany as needed. Subsequently, the analysis of multiple styles compared revealed that the beers that had undergone this process were much clearer.
Lagering is a step that must be carried out before bottling the beer, that is when the fermentation is over. In the case of using a flat bottom fermenter, it is best to do it in the second fermenter
Put the fermenter in a place with a temperature close to zero but not lower, otherwise the beer will freeze. It is left at this temperature for 1-2 months and then proceeds as usual: a final racking is made before adding the priming sugar and everything is bottled. Don't worry about the yeast cells because, if you put the right amount of yeast in the beginning, there will be enough to reactivate the re-fermentation in the bottle. However, if you are afraid that they have precipitated excessively and that therefore the re-fermentation could struggle to start, you can add a little yeast in the fermenter (obviously after racking) respecting the recommended doses for re-fermentation in the bottle.
LAGERING IN BOTTLE
In recent years, a variant of the original technique has become widespread: bottled lagering. Practically in this case, instead of carrying out this step before bottling, it is done after maturation. So when the bottles have reached the right sparklingness and aromatic profile, the bottles will be moved to a place close to 0 °C to proceed with the lagerization for 1-2 months. Even if the conservation of the finished beer is much longer, this technique has a flaw: the yeasts will always remain in the bottle, so when we go to pour the beer we will have to be very careful not to move them excessively, so as not to end up in the glass.
Many homebrewers in lager production make a stop during fermentation to eliminate diacetyl residues, called diacetyl rest. This technique consists in raising the temperature of the fermenter for 24 hours, bringing it to about 18 °C. In our case, it will therefore be carried out when the fermentation is over and immediately before the lagerization. However, this is a step that can be taken in the production of any lager, even in those that will not have to remain in the cold for several months: just raise the temperature for 24 hours before bottling.
This is a step which, however, is not always necessary: you have to look at the type of yeast used and its diacetyl production. Our senses should also guide us: if too much diacetyl has formed, the smell of butter should be recognizabYle by smelling the beer. Only in this case it is important to do the diacetl rest, otherwise it is just an additional step that can or cannot be done, depending on the time we have available.
LAGERING OR WINTERIZATION?
We often hear about winterization or even cold crash. It is the same thing and we can almost call it a kind of brief lagering method. In fact, this step always involves bringing the beer to temperatures close to zero, but leaving it at these temperatures for only 3 days. The final beer will not be as clean as in the case of lagering but it is an excellent compromise in terms of time. Furthermore, the other great advantage of winterization is that it can be carried out for any type of fermentation, whether low or high